1. Field of the Invention
The present invention relates to techniques for applying heat-transfer materials. More specifically, the present invention relates to a system and method for applying a liquid-metal thermal-interface material.
2. Related Art
The functionality, performance, and operating speed of integrated circuits (ICs) have increased significantly in recent years. This has resulted in significantly increased power consumption and associated heat generation in these devices. Consequently, it is becoming a considerable challenge to maintain acceptable internal and external operating temperatures in these ICs.
One approach to managing the increasing thermal load is to use an improved thermal-interface material between a semiconductor die in an IC and an external environment (such as the IC package). Proper operation of the semiconductor die over a range of operating conditions determines several required properties for a candidate thermal-interface material. In particular, the thermal-interface material should not contain impurities and should not damage the semiconductor die. Moreover, the thermal-interface material should have a high bulk thermal conductivity and should conform to a surface of the semiconductor die at ambient or low pressure, thereby ensuring a low thermal impedance between the external environment and the semiconductor die.
Several liquid metals are promising candidates as improved thermal-interface materials. In principle, these liquid metals can meet the required properties, if the liquid metals are dispensed in a controlled manner. However, it is often difficult to work with liquid metals. For example, liquid metals do not wet with many materials. Consequently, it may be difficult to fabricate a thin layer of liquid metal that conforms to the surface of the semiconductor die. Moreover, many liquid metals are highly corrosive and/or dissolve other metals, which makes them extremely difficult to handle during manufacturing. This can increase the complexity and the cost of the manufacturing processes, which are obstacles to the use of these improved thermal-interface materials.
Hence what is needed are techniques for applying liquid metals without the problems listed above.